1. Field of the Invention
The present invention relates to an apparatus and method for testing an electrode structure for a thin display device using a MISFET function.
2. Description of the Related Art
A thin display has been manufactured as a display for a television and a personal computer. As a method of evaluating the electrode structure for such a thin display device, there are known an operational test, a reliability test, and an appearance test. In particular, a conventional test for checking a lighting operation is carried out after a completion of a product.
FIG. 1 shows a conventional method of testing an electrode structure for a thin display device. In the conventional example, the electrode structure for the thin display device such as a liquid crystal display panel is described as an example. The testing method shown in FIG. 1 is referred to as a probing method. In the probing method, the electrode, structure for the thin display device has pixel electrodes arranged in a matrix of n rows and m columns (n and m are integers). Gate electrode wiring lines 83 and source electrode wiring lines 85 are arranged on a substrate 86 to extend longitudinally and laterally between TFT transistors 80.
In this testing method, probes 81 and 82 are set to contact the gate and source voltage wiring lines 83 and 85, to detect output voltages, respectively. Thus, disconnection of the wiring line to the pixel electrode 84, and short-circuit between pixel electrodes are tested. In short, in this method, a defect of the pixel electrode 84 is detected by applying a test signal to the source voltage wiring line 85 and the gate voltage wiring line 83 formed on the electrode structure for the thin display device.
However, the probing method faces the increase of contact errors of the probes and high exchange frequency of the probes, as the electrode structure for the thin display device is made larger. This results in the increase in its maintenance cost.